Outbreak of Ralstonia mannitolilytica in immunocompromised patients associated with a contaminated drug

Objective: Ralstonia mannitolilytica is a bacterium capable of contaminating various drugs and medical products, leading to healthcare-associated infections outbreaks. This study describes an outbreak caused by this microorganism that was controlled through an epidemiological investigation and the identification of contaminated dexamethasone ampoules as the source. Methods: a retrospective descriptive analysis of R. mannitolilytica infections cases was conducted in as 80-bed terciary care institution during August 2023. All affected patients were women undergoing chemotherapy treatment, either hospitalized in the general ward or attending the day hospital. All patients with positive cultures for R. mannitolilytica were included. An epidemiological analysis of the cases and bacteriology testing on pharmaceutical products were performed to identify possible sources of infection. Results: Six patients presented with chemotherapy-catheter-related infections and positive cultures for R. mannitolilytica. These patients were undergoing different chemotherapy treatments, but they shared two common drugs: dexamethasone in ampoules and sodium heparin in ampoules. Upon analysis, growth of R. mannitolylitica was found in the 2 ml ampoules of a specific batch of dexamethasone. Conclusion: R. mannitolylitca is a bacterium that can grow in media with few nutritional requirements, and hospital outbreaks are a reality. It is important to quickly control these events to avoid further occurrences.